Method and system for operating system recovery from a network device including user selectable options for storing an OS image in local storage of a caching device

ABSTRACT

Methods and systems for a network device are provided. The network device includes a storage protocol controller having a port for interfacing with a storage area network (SAN) based storage device; a processor executing instructions for managing a local storage device that is configured to operate as a caching device for a computing device. The local storage device is used to store a recovery copy of an operating system of the computing device, where the recovery copy is accessible via a processor executable basic/input output (BIOS) utility.

TECHNICAL FIELD

The present disclosure relates to computing system and methodsassociated with recovering a corrupt operating system.

BACKGROUND

A computer network, often simply referred to as a network, is a group ofinterconnected computers and devices that facilitates communicationamong users and allows users to share resources. Adapters, switches andother devices are typically used during network communication forreading and writing data at mass storage devices.

Computing devices (or systems) use an operating system for managingoverall computing device operations. It is desirable to have a redundantcopy of the operating system in case an original version becomescorrupt. Continuous efforts are being made to efficiently provide accessto operating system copies.

BRIEF DESCRIPTION OF THE DRAWINGS

The various present embodiments relating to the management of networkelements now will be discussed in detail with an emphasis onhighlighting the advantageous features. These novel and non-obviousembodiments are depicted in the accompanying drawings, which are forillustrative purposes only. These drawings include the followingfigures, in which like numerals indicate like parts:

FIG. 1A is a functional block diagram of a system, used according to oneembodiment;

FIG. 1B shows an example of an intelligent storage adapter (ISA);

FIG. 1C shows an example of a configuration for using the ISAs,according to one embodiment;

FIG. 2 shows an example of storing an operating system at a local cachemanaged by the ISA; and

FIGS. 3 and 4 show process flow diagrams, according to one embodiment ofthe present disclosure.

DETAILED DESCRIPTION

The following detailed description describes the present embodimentswith reference to the drawings. In the drawings, reference numbers labelelements of the present embodiments. These reference numbers arereproduced below in connection with the discussion of the correspondingdrawing features.

As a preliminary note, any of the embodiments described with referenceto the figures may be implemented using software, firmware, hardware(e.g., fixed logic circuitry), manual processing, or a combination ofthese implementations. The terms “logic,” “module,” “component,”“system,” and “functionality,” as used herein, generally representsoftware, firmware, hardware, or a combination of these elements. Forinstance, in the case of a software implementation, the terms “logic,”“module,” “component,” “layer,” “system,” and “functionality” representexecutable instructions that perform specified tasks when executed on ahardware based processing device or devices (e.g., CPU or CPUs). Theprogram code can be stored in one or more non-transitory, computerreadable memory devices.

More generally, the illustrated separation of logic, modules,components, systems, and functionality into distinct units may reflectan actual physical grouping and allocation of software, firmware, and/orhardware, or can correspond to a conceptual allocation of differenttasks performed by a single software program, firmware program, and/orhardware unit. The illustrated logic, modules, components, systems, andfunctionality may be located at a single site (e.g., as implemented by aprocessing device), or may be distributed over a plurality of locations.The term “machine-readable media” and the like refers to any kind ofmedium for retaining information in any form, including various kinds ofstorage devices (magnetic, optical, static, etc.).

The embodiments disclosed herein may be implemented as a computerprocess (method), a computing system, or as an article of manufacture,such as a computer program product or computer-readable media. Thecomputer program product may be non-transitory, computer storage media,readable by a computer device, and encoding a computer program ofinstructions for executing a computer process. The computer programproduct may also be readable by a computing system, and encoding acomputer program of instructions for executing a computer process.

In one embodiment, an adapter, for example, a network device isprovided. The adapter includes a storage protocol controller having aport for interfacing with a storage area network (SAN) based storagedevice and another adapter operating within a cluster is provided. Theadapter includes a processor executing instructions for managing a localstorage device that is configured to operate as a caching device for acomputing device. The adapter operates as a host bus adapter and astorage controller for managing storage space at the local storagedevice and the SAN-based storage device.

System 100:

FIG. 1A is a block diagram of a system 100 configured for use with thepresent embodiments. System 100 may include a plurality of computingsystems 102A-102N (may also be referred to as server (s) 102 or hostsystem 102), each coupled to an adapter 114 (also referred to as anintelligent storage adapter (ISA) 114) that interfaces with otherdevices and ISAs, as described below in more detail.

The computing system 102A may include one or more processors 104, alsoknown as central processing units (CPUs). Processor 104 may be, or mayinclude, one or more programmable general-purpose or special-purposemicroprocessors, digital signal processors (DSPs), programmablecontrollers, application specific integrated circuits (ASICs),programmable logic devices (PLDs), or the like, or a combination of suchhardware devices.

Processor 104 executes machine implemented instructions (or processsteps/blocks) out of a memory 106 and interfaces with an interconnect107 that may be referred to as a computer bus 107. The computer bus 107may be, for example, a system bus, a Peripheral Component Interconnect(PCI) bus, PCI-Express (PCIe) bus, a HyperTransport or industry standardarchitecture (ISA) bus, a SCSI bus, a universal serial bus (USB), anInstitute of Electrical and Electronics Engineers (IEEE) standard 1394bus (sometimes referred to as “Firewire®”), or any other type of bus.

The computing system 102A may further include a storage device 108,which may be for example a hard disk, a CD-ROM, a non-volatile memorydevice (flash or memory stick) or any other storage device for storingstructured or unstructured data. Storage 108 may store operating systemprogram files (or data containers), application program files, forexample, email applications, database applications, managementapplications, and other application files. Some of these files arestored on storage 108 using an installation program. For example, theprocessor 104 may execute computer-executable process steps of aninstallation program so that the processor 14 can properly execute theapplication program.

In one embodiment, storage device 108 may be a solid state storagedevice (may also be referred to herein as SSD 108). SSDs are becomingpopular for servers that may need to store large amounts of data. ISA114 described below in more detail may be used to manage and/or accessstorage device 108, according to one embodiment.

Memory 106 also interfaces with the computer bus 107 to provide theprocessor 104 with access to memory storage. Memory 106 may includerandom access main memory (RAM). When executing storedcomputer-executable process steps from storage 108, the processor 104may store and execute the process steps out of memory 106. Read onlymemory (ROM, not shown) may also be used to store invariant instructionsequences, such as start-up instruction sequences or basic input/outputsystem (BIOS) sequences for operation of a keyboard (not shown).

In one embodiment, processor 104 may execute an application 105 forperforming certain functions. For example, application 105 may be adatabase application, a virtual machine executed in a virtualenvironment (provided by VMware Corporation, Microsoft Corporation orany other entity) electronic email application (for example, MicrosoftExchange) or any other application type. Application 105 may issue readand write requests that are processed by ISA 114, as described below inmore detail. Application 105 may also be referred to as a “client”.

The computing system 102A also includes other devices and interfaces109, which may include a display device interface, a keyboard interface,a pointing device interface and others. The details of these componentsare not germane to the inventive embodiments.

ISA 114 may be configured to handle both network and storage trafficwhile interfacing with other elements. In one embodiment, as describedbelow in detail, ISA 114 may be configured to provide the functionalityof a host bus adapter (HBA) by providing connectivity to SAN (storagearea network) based storage arrays as well as present logical storagefrom a local storage device connected to the ISA. Various network andstorage protocols may be used to handle network and storage traffic, forexample, Ethernet, Fibre Channel, Fibre Channel over Ethernet (FCoE),Internet over Small Computer System Interface (iSCSI), and others. Someof the common protocols are described below.

Ethernet is a common network protocol used for network communication.The original Ethernet bus or star topology was developed for local areanetworks (LAN) to transfer data at 10 Mbps (mega bits per second). NewerEthernet standards (for example, Fast Ethernet (100 Base-T) and GigabitEthernet) support data transfer rates that are greater than 1 gigabit(Gb). The various embodiments described herein may use Ethernet (whichincludes 100 Base-T and/or Gigabit Ethernet) as the network protocol.However, the adaptive embodiments disclosed herein are not limited toany particular protocol, as long as the functional goals are met by anexisting or new network protocol.

Fibre Channel (may also be referred to as “FC”) is a common storageprotocol used in SANs. Fibre Channel is a set of American NationalStandards Institute (ANSI) standards that provide a serial transmissionprotocol for storage and network protocols such as HIPPI, SCSI, IP, ATMand others. Fibre Channel supports three different topologies:point-to-point, arbitrated loop and fabric. The point-to-point topologyattaches two devices directly. The arbitrated loop topology attachesdevices in a loop. The fabric topology attaches host systems directly(via HBAs) to a fabric, which are then connected to multiple devices.The Fibre Channel fabric topology allows several media types to beinterconnected. Fibre Channel fabric devices include a node port or“N_port” that manages Fabric connections. The N_port establishes aconnection to a Fabric element (e.g., a switch) having a fabric port orF_port.

A new and upcoming standard, called Fibre Channel over Ethernet (FCOE)has been developed to handle both Ethernet and Fibre Channel traffic ina storage area network (SAN). This functionality would allow FibreChannel to leverage high speed, for example, 10 Gigabit Ethernetnetworks while preserving the Fibre Channel protocol. In one embodiment,ISA 114 can be configured to operate as a FCOE adapter. Those ofordinary skill in the art will appreciate, however, that the presentembodiments are not limited to any particular protocol.

iSCSI is an IP based storage networking standard for linking datastorage facilities. By carrying SCSI commands over IP networks, iSCSI isused to facilitate data transfers over intranets and to manage storageover long distances. iSCSI can be used to transmit data over local areanetworks (LANs), wide area networks (WANs), or the Internet and canenable location-independent data storage and retrieval. The protocolallows clients to send SCSI commands (referred to as command or(control) data blocks (CDBs) to SCSI storage devices (may be referred toas targets) on remote servers. iSCSI is a SAN-based protocol, allowingorganizations to consolidate storage into data center storage arrayswhile providing hosts (such as database and web servers) with theillusion of locally attached disks. Unlike traditional Fibre Channel,which uses special-purpose cabling, iSCSI can be run over long distancesusing existing network infrastructure. In one embodiment, ISA 114 mayoperate as an initiator as well as a target for responding toinput/output (referred to as I/O or “IO”) requests for reading andwriting information at storage devices.

Storage space at a storage device (local or SAN-based) is typicallypresented to application 105 as a logical entity referred to as alogical unit number (LUN). Each LUN is uniquely identified by anidentifier (LUN ID) and is associated with physical storage space. A LUNhas a size associated with it that may indicate the amount of storagespace that is made available to a computing system and a drive letterthat may be used to access the LUN.

A LUN is typically divided into logical block addresses (LBAs) that areused by application 105 to read and write data to storage locations. TheLBAs are mapped with actual physical storage to read and write data. ALUN used by an application may be referred to as a data LUN. A LUN thatis accessible via a SAN connection may be referred to as a SAN LUN. ALUN at a local storage device managed by ISA 114 may be referred to as“cache” LUN. A cache LUN may be used to cache data stored at a SAN LUNor another data LUN. The cache LUN is managed by ISA 114 and may not bevisible to application 105.

Referring back to FIG. 1A, computing system 102 uses an adapterinterface 110 to communicate with ISA 114 via a link 112. In oneembodiment, link 112 may be a PCI-Express link or any other interconnecttype. The adaptive embodiments disclosed herein are not limited to anyparticular link type.

ISA 114 may communicate and interface with a mass storage system 120 viaa SAN 116 that may include one or more switches (may be referred to asfabric switch). The mass storage system 120 may include a plurality ofstorage devices 124A-124N. Storage space at storage devices 124A-124Nmay be presented as SAN LUNs to application 105 via SAN 116. Controller122 of mass storage system 120 may be used to manage storage devices124A-124N. In one embodiment, controller 122 may include a processor, anISA 114 and other similar components.

System 100 may also include a management console 118, used according toone embodiment. Management console 118 may be a computer system similarto computing system 102A described above in detail. Management console118 executes a management application 117 that may be used to configurestorage space as logical structures (for example, as LUNs) that arepresented to computing systems 102A-102N for storing information or ascache LUNs at local storage for caching information stored at SAN LUNs.Permissions associated with a LUN may also be configured usingmanagement application 117. The permissions indicate which entities maybe allowed to access a LUN to read and/or write information. Managementapplication 117 may store LUN attributes and permissions in aconfiguration data structure 117A at a storage location.

In one embodiment, ISA 114 is provided that can provide transparent datacaching at SSDs while efficiently synchronizing the SSD data withSAN-based storage devices. The ISA enables management of data stored atthe SSDs. The ISA also enables the SSDs to be shared as SAN storageallowing other servers 102B-102N to access data residing at SSDs inserver 102A. ISA 114 may configure a LUN from the local storage 108 andpresent the LUN to servers 102A-102N, allowing the local storage 108 tobe shared by other servers 102B-102N.

In another embodiment, ISA 114 provides traditional SAN connectivity tocomputing system 102A and to the SSDs at each computing system. The SSDsmay be managed as a storage pool that may be configured to operate as acache pool to cache read/write data for SAN LUNs presented to thecomputing systems. SAN LUNs when configured may be tagged with anattribute that allows caching at the local SSDs for read and/or writecaching.

FIG. 1B shows an example of ISA 114A that includes a storage protocolcontroller 128 (shown as “external storage protocol controller”) withports 126A and 126B. The storage protocol controller may be a FibreChannel controller (or application specific integrated circuit (ASIC))that is available from QLogic Corporation for interfacing with FibreChannel based storage devices via ports 126A/126B. Ports 126A/126Binclude logic and circuitry for sending and receiving Fibre Channelframes. Fibre Channel is simply shown as an example and the variousembodiments disclosed herein are not limited to any particularstorage/network protocol. Thus, ports 126A-126B are not limited to justFibre Channel ports. Furthermore, although only two ports 126A and 126Bare shown as an example, the adaptive embodiments disclosed herein arenot limited to any particular number of ports.

Storage protocol controller 128 may operate as a host bus adapter formanaging I/O requests for SAN-based storage. Storage protocol controller128 is configured to process I/O requests for reading data fromSAN-based storage (124A-124N) and writing data to SAN-based storage.Thus storage protocol controller 128 is used to take advantage ofexisting SAN infrastructure, while providing access to SSDs forcomputing systems 102A-102N.

In one embodiment, storage protocol controller 128 includes a processor(not shown) for executing a Fibre Channel stack having layers, FC0-FC4.FC0 is defined by the Fibre Channel specification as the physical layer,which includes cables (fiber optics, twisted-pair), connectors andothers. FC1 layer is defined as the data link layer. This layerimplements 8B/10B (8-bit to 10-bit) encoding and decoding of signals.FC2 layer is defined as the network layer. This layer defines the mainFibre Channel framing, addressing, and control protocols. FC3 layer isan auxiliary layer that provides common services like encryption or RAIDrelated. FC4 layer is the protocol mapping layer where other protocols,such as SCSI are encapsulated into an information unit for delivery toFC2 and transmission across a Fibre Channel network. This layer providesflexibility to Fibre Channel as a networking technology compatible withother technologies.

ISA 114A also includes a host interface 150 that interfaces withprocessor 104 via link 112. The structure of host interface 150 willdepend on the type of connection/interconnect used to communicate withprocessor 104. For example, if a PCI-Express link is used to communicatewith processor 104, then host interface 150 includes logic and circuitryfor receiving and sending PCI-Express packets/information.

ISA 114A includes a system on chip (SOC) 131 that includes amicroprocessor 130 having access to an adapter memory (may also bereferred to as local memory) 132. Processor 130 may be one or moreprogrammable general-purpose or special-purpose microprocessors, digitalsignal processors (DSPs), programmable controllers, application specificintegrated circuits (ASICs), reduced instruction set computer (RISC),programmable logic devices (PLDs), or the like, or a combination of suchhardware devices. Memory 132 may be used to store firmware instructionsand various data structures for ISA 114A for controlling overall ISA114A operations. Memory 132 may also store instructions for implementingthe various embodiments described herein.

SOC 131 may also include a receive module 134 and a transmit module 136.The receive module 134 may be used to store packets that are receivedvia ports 126A/126B, while transmit module 136 may be used to storeinformation that is transmitted via ports 126A/126B or to local SSDsthat are described below. Receive module 134 and/or transmit module 136may be separate modules and may include more than one component forprocessing received information or information that is transmitted.

ISA 114A may also include a non-volatile memory 138 (shown as flashmemory) for storing parameters/instructions that may be used bymicroprocessor 130 for executing the instructions described below indetail. ISA 114A also includes a storage connector 140 that interfaceswith another card 141 (may also be referred to as a daughter card 141),according to one embodiment. In one embodiment, the storage connectormay be a PCI-Express connector, PCI connector or any other connectortype based on the interconnect used by SOC 131 to interface with theSSDs. The daughter card 141 includes a memory controller 142 thatinterfaces with a plurality of connectors 144A-144N. The plurality ofconnectors 144A-144N are used to plug in SSDs 148A-148N (similar tostorage 108). In this embodiment, SSDs 148A-148N are included within aserver chassis 146. In one embodiment, connectors 144A-144N may beSerial Advanced Technology Attachments (or Serial ATA or SATA) forreceiving SSDs 148A-148N. In another embodiment, connectors 144A-144Nmay be Serial Attached SCSI (or SAS) connectors.

ISA 114A has SAN connectivity because of ports 126A-126B, similar to ahost bus adapter, as mentioned above. The storage protocol controller128 allows SAN storage based processing. Unlike conventional HBAs, ISA114A also includes a storage connector 140 that provides local storagesolutions via SSDs 148A-148N.

In another embodiment, ISA 114A is configured such that a daughter cardhas the SSDs 148A-148N on the card itself, rather than on the serverchassis 146. In another embodiment, ISA 114A is configured such that thememory controller 142 is on the same card as the other components of ISA114A. The SSDs 148A-148N are also on the same card connected via one ormore storage connectors.

FIG. 1C shows a system 100A where each ISA 114B-114D (similar to ISA114A described above) in servers 102A-102C are coupled to a fabricswitch 160, according to one embodiment. Fabric switch 160 includes aplurality of ports 160A-160E. Ports 160A-160C are coupled to ISA114B-114D ports, respectively, while port 160D is coupled to controller122 of the mass storage system 120. Management console 118 may becoupled to port 160E for configuring various components of system 100A.

Management console 118 may also be used to configure LUNs 156A-156N thatare presented to servers 102A-102N for storing information. The LUNs maybe based on storage located at SAN-based storage 120 or at a local SSD148A-148N.

The LUNs 156A-156N may be configured to operate as a local LUN. In thisconfiguration, the LUN may be used as a “boot” LUN. The LUN may be usedby the host computing system to which it is presented. One or more ISAsmay present the boot LUN to any of the servers that are served by acluster of ISAs. LUNs 156A-156N may also be configured as a SAN mirrorLUN. In such configuration, the LUN is a mirror of a LUN that isassociated with a SAN-based storage device. LUNs 156A-156N may also beconfigured as Peer Mirror LUN. In such a configuration, the LUN ismirrored across at least two ISAs and hence can be made accessible to atleast two servers.

The LUNs 156A-156C may also be accessible by one or more servers via SAN116. In this example, a DAS (direct attached storage) based SSD becomesaccessible as SAN storage, while the DAS based storage is still managedby an application 105 (for example, a database application).

In FIG. 1C, one embodiment of ISA 114B in server 102A acts as a storageprotocol controller for LUN 156A, serving up LUN 156A to initiators ISA114C in server 102B and ISA 114D in server 102C. At the same time, ISA114B also acts as a traditional HBA (initiator) for SAN LUNs at SANstorage devices 124A-124N. In one embodiment, SSD 148 may be used tostore an operating system (OS) for the host system.

FIG. 2 shows an example of storing a native image of the operatingsystem 202 at a first storage location and a back-up image 204 at asecond storage location of SSD 148. The OS and the backup images areaccessible via the basic input/output instructions (BIOS) of the ISA114. BIOS 206 allows a user using a utility to select an option forstoring the native image as well as for the backup image. For example,option 1 of the native image may be the latest operating systeminstallation copy, a fully configured operating system or any otherversion. Option 1 for the backup copy may also be a clone of the latestcopy of an installed operating system, a snapshot of a fully configuredoperating system, an image of a semi-configured operating system and soforth.

FIG. 3 shows a process 300 for installing an operating system at SSD148, according to one embodiment. The install process begins in blockB302 and may be initiated by using a processor executable utilityprogram that is presented to a user. The user interface may be a commandline interface (CLI) or a graphical user interface (GUI). In block B304,the user initiates an operating system install operation at the localcache 148. The user chooses to use the local cache managed by the ISA114 to store the copy of the operating system.

In block 306, the user selects one of the operating system options forstoring the operating system image. The option includes a freshinstalled copy of the operating system, a fully configured copy of theoperating system that may include applications and other programs or anyother configuration of the operating system.

In block B308, the selected configuration type is installed at the localcache 148. Thereafter in B310, a backup point i.e. a clone or snapshotof the image is generated. A clone is an exact copy of the operatingsystem that is being installed at local cache 148. The clone can bemodified snapshot is an image the current state of the operating systemand is typically a read-only copy of the data. This can be incrementalby capturing only changes from previous state and not the whole stateagain. Then, in block B312, the backed up copy is stored as a recoverycopy and the process ends in block B314.

FIG. 4 shows a process flow 400 for recovering a crashed or corruptedcopy of an operating system, according to one embodiment. The processbegins in block B402. In block B404, the process determines if a nativeoperating system copy is corrupt or has failed. If not, then the hostsystem is booted using the native image, in block B406. If yes, then inblock B408, a recovery image is selected from the local cache 148 thatis managed by the ISA 114. The image that the user selects may be afully configured version of the operating system, from a “fresh”installed version of the operating system. In one embodiment, theprocess allows a user to use a clone or a snapshot image of theoperating system. Thereafter, the boot operation is completed in blockB410 and the process ends at block B412.

In one embodiment, redundancy is provided for an operating system for ahost computing system. The operating system is protected at a localcache managed by the ISA 114. Even if a primary image fails, thecomputing system can use a secondary image to boot. Because the user maynot use the local cache to store data, it can be safely used to storeoperating system and an image of the operating system.

Although the present disclosure has been described with reference tospecific embodiments, these embodiments are illustrative only and notlimiting. For example, although the description above has been describedwith respect to an ISA, any other device may be configured to performthe foregoing function. Thus the term adapter and device areinterchangeable. Many other applications and embodiments of the presentdisclosure will be apparent in light of this disclosure and thefollowing claims. References throughout this specification to “oneembodiment” or “an embodiment” means that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics being referred to maybe combined as suitable in one or more embodiments of the disclosure, aswill be recognized by those of ordinary skill in the art.

What is claimed is:
 1. A network device, comprising: a storage protocolcontroller having a port for interfacing with a storage area network(SAN) based storage device; and a processor executing instructions formanaging a local storage device of the network device that is configuredto operate as a caching device for a computing device; wherein the localstorage device of the network device is used to store a recovery copy ofan operating system of the computing device, where the recovery copy isaccessible via a processor executable basic/input output (BIOS) utility;wherein the recovery copy of the operating system is based on a userselectable option for storing an image of the operating system.
 2. Thenetwork device of claim 1, wherein the recovery copy is accessed to bootthe computing device, when a primary image of the operating systembecomes unavailable.
 3. The network device of claim 1, wherein thenetwork device operates as a host bus adapter for processinginput/output requests for reading and writing information.
 4. Thenetwork device of claim 1, wherein the storage protocol controller is aFibre Channel controller.
 5. The network device of claim 1, wherein thenetwork device presents storage space at the local storage device as alogical object to other computing devices.
 6. The network device ofclaim 5, wherein the other computing devices use the local storagedevice as a caching device for caching information that is stored at theSAN based storage device.
 7. A machine implemented method, comprising:managing a local storage device of a network device that is configuredto operate as a caching device and as a host bus adapter for accessing astorage area network (SAN) based storage device; and using the localstorage device of the network device to store a recovery copy of anoperating system of a computing device, where the recovery copy isaccessible via a basic/input output (BIOS) utility instructions executedby a processor out of a memory device; wherein the recovery copy of theoperating system is based on a user selectable option for storing animage of the operating system.
 8. The method of claim 7, wherein therecovery copy is accessed to boot the computing device when a primaryimage of the operating system becomes unavailable.
 9. The method ofclaim 7, wherein a storage protocol controller having a port interfaceswith the SAN based storage device to provide access to SAN basedstorage.
 10. The method of claim 9, wherein the storage protocolcontroller is a Fibre Channel controller.
 11. The method of claim 7,wherein the network device presents storage space at the local storagedevice as a logical object to other computing devices.
 12. The method ofclaim 11, wherein the other computing devices use the local storagedevice as a caching device for caching information that is stored at theSAN based storage device.
 13. A non-transitory, machine readable storagemedium, storing executable instructions, which when executed by amachine, causes the machine to perform a method, the method comprising:managing a local storage device of a network device that is configuredto operate as a caching device and as a host bus adapter for accessing astorage area network (SAN) based storage device; and using the localstorage device of the network device to store a recovery copy of anoperating system of a computing device, where the recovery copy isaccessible via a basic/input output (BIOS) utility instructions executedby a processor out of a memory device; wherein the recovery copy of theoperating system is based on a user selectable option for storing animage of the operating system.
 14. The storage medium of claim 13,wherein the recovery copy is accessed to boot the computing device whena primary image of the operating system becomes unavailable.
 15. Thestorage medium of claim 13, wherein a storage protocol controller havinga port interfaces with the SAN based storage device to provide access toSAN based storage.
 16. The storage medium of claim 15, wherein thestorage protocol controller is a Fibre Channel controller.
 17. Thestorage medium of claim 13, wherein the network device presents storagespace at the local storage device as a logical object to other computingdevices.